Effects of increased central dopaminergic tonus on gonadotropin secretion.
Gonadotropin secretion was investigated in 10 healthy volunteers (5 men and 5 women in the early follicular phase of cycle) by the following procedures: i) infusion of saline over 4 1/2 h period; ii) infusion of dopamine (DA) 4 microgram/kg bw/min over 4 h period; iii) oral administration of L-dopa (D) 100 mg plus carbidopa (C) 35 mg after 24 h pretreatment with C 50 mg every 6 h. This last pharmacological approach selectively enhances the central dopaminergic tonus. Blood samples were withdrawn every 15 min over 4 1/2 h period. No ultradian periodicity in LH and FSH secretion was observed. No significant modification in serum FSH levels was induced by any treatment at any time, while a significant decrease in serum LH concentration was observed from 45 to 240 min during DA infusion (-46.8%; p less than 0.005) and from 60 to 240 min after D + C administration  -41.5%; p less than 0.05). These data demonstrate that, in humans, acute dopaminergic stimuli have an inhibitory action on LH release and suggest that this inhibition is exerted at the central level.
D000284:Administration, Oral; D000328:Adult; D002230:Carbidopa; D004298:Dopamine; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood*; D006801:Humans; D007980:Levodopa; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male
D007980:Levodopa; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D002230:Carbidopa; D004298:Dopamine